Floor Pan Questions

[hchiuraz]

Hey everyone,

Just a general question, but can anyone direct me to a good source of information for a how-to on replacing floor pans?

I recently bought a 78, cleared out the drivers side and found not a speck of rust at all and then got to the passanger side and discovered a seriously failing t top weather seal. Low and behold.. the floor pan needs some help. Actually, the rust is not that bad and really could be patched but I am just going to replace the whole pan anyways.

I've already got the replacement pan and someone coming to weld it for me next week. I want to learn how weld, but maybe not on this project ;o) What I really want to know though, is the prep and after-installation details.

Thanks!
-Heather

[Da_Raabi]

It depends on how you want to do the pan. There are two types of weld commonly done on floor pans, the butt and the seam. Essentially the difference is a butt weld is where two pieces of metal are brought together on a common line. The welding is more difficult, but it looks perfect when done. The seam weld is where you leave a little bit (approx 1-3") of the old floor around the edges of the piece, and lay the new piece over it, welding once for each edge (top and bottom). The big thing here is that it leaves a pocket between the layers that needs to be protected, mainly by a quality weld-through primer.

A complete floor can be difficult and time consuming, if you are having someone do it, it can get expensive in man hours. I had a lot of rust on my floors, but I patched it all up with smaller pieces and a $100 harbor freight stick welder. I had no welding experience, but it came out OK.

Is there a reason you are choosing to do the whole pan? If you only need to patch a few holes, then do it that way, it is much easier and there is a smaller chance of messing things up, plus it may be a great way for you to learn to weld. Remember floors are the best place to learn, because no-one can see them!

[Cmatt1605]

last owner "riveted" mine on.....over top of the rust holes too....DON'T DO THAT. on my to-do list to fix

[TX79Z28]

I am not sure if you are cutting the old one off, but as Da Raabi said, there are two very distinct methods and each one would require different cutting (leaving overlap or not obviously). Either way, the only thing that could be messed up would be the floor brace that runs from rocker to rocker, be VERY careful around them! Also, the obvious like fuel and brake lines, they are pretty well tucked away, but I would make sure you are mindful of them as you start cutting

Not sure how much of the project you are doing yourself, but I would say that I would leave the cutting to the person that is doing the welding, especially if they are going to butt welded it.

As far as prep, other than the obvious removal of EVERYTHING (especially flammable material), the only thing I would do would be to grind all the areas to make sure you are not missing areas that need patching beyond the reach of the floor pan. In mine, and from what I see from others here, if you see a pin hole....there is ALWAYS more!

I did the entire front section (from the front of the rear seats to the toe boards) and it CAN be a project! I second the opinion that if you don't absolutely need to do the whole floor.....don't.

[David79Z28]

I asked a similar question recently. Several good comments here.

http://www.nastyz28.com/forum/showthread.php?t=245152

[krabben1]

If you do a general search on the website,youll also get project progress stuff with pics.Thats where it all happens.

[onelapduster]

http://www.nastyz28.com/forum/showth...=238611&page=2

Check out the second page, I just did passenger side floors in my Firebird. I could have done a full floor pan. I already had the rear pan but cut it to only patch what was needed. Reason for this was it was less work trying to get it to fit around the seat belt hole. I used the butt weld method as for me it is easier to clean up on either side and allows for me to see where I have missed. As you can see, I didnt bother grinding the welds, because 1. they will be covered, 2. I didnt care. The butt weld on the opposite side once painted doenst even look like its been patched.